Effects of Hard Fats on In Vitro and In Vivo Rumen Fermentation ' Milk Production, and Reproduction in Dairy Cows1 J. D. FERGUSON,2 D. SKLAN,3 W. V. CHALUPA,2 and D. S. KRONFELD4 Department of Clinical Studies New Bolton Center University of Pennsylvania School of Veterinary Medicine Kennett Square 19382
and Faculty of Agriculture Hebrew University Rehovot 76-100. Israel
ABSTRACT
90 d postcalving. In Pennsylvania, prilled fat had variable effects on milk composition and little effect on milk yield and FCM. Conception rate was improved in cows consuming rations containing prilled fat: first service, 59.1 versus 42.6%; all services, 59.3 versus 40.7%. The inclusion of prilled fat at 2% of DM in dairy cattle rations had slight effects on rumen fermentation, variable effects on milk. yield and composition, and beneficial effects on conception rate. (Key words: dairy cattle, hard fats, production, reproduction)
Adding 0, 5, 10, 15, and 20% of substrate as prilled or unprilled fatty acids [palmitic (47 to 48%), stearic (36 to 37%), and oleic (14%) acids] to an in vitro rumen fennenter had no effect on total VFA production. Acetate:propionate ratio was reduced by fatty acid concentrations of 15 and 20% (prilled and unprilled). In a 4 x 4 Latin square, increasing dietary prilled fatty acids (0, 3, 6, or 9% of OM) decreased OM intake, increased percentage of milk. fat, and had no effect on percentage of milk. protein. Milk. volume and FCM increased with 3% but decreased with 6 and 9% dietary fatty acids. Rumen fluid acetate:propionate decreased with increasing dietary fatty acids. Holstein cows in three herds in Pennsylvania and Friesian cows in an Israeli herd were assigned randomly to receive, from 0 to 110 to 150 d postcalving, diets containing 0 or 2% of OM prilled fat. In Israel, dietary fat increased milk. yield, FCM, and fat percentage during the first
INTRODUCTION
Received September 18, 1989. 1"ceepted May 9, 1990. This research was supported by Grant Number US722-83c from BARD-The United States-Israel Binational A~cu1tuIa1 Research and Development Fund. Present address: Center for Animal Disease and Pr0ductivity, New Bolton Center. University of Peonsylvania, School of Veterinary Medicine, Kennett Square 19382. ~ebrew University of Jerusalem, The Levi Eshkol School of Agriculture, Rehovot, Israel 76-100. ~ent address: Virginia Tech University, Department of Animal Science, Blacksburg, VA 24061-0306. 1990 J Dairy Sci 73:2864-2879
Inclusion of fat, especially rumen inert fat (3, 6, 17, 24), in dairy cattle rations has four immediate benefits: 1) increased caloric density without compromising fiber (11, 19, 24); 2) increased energy intake for higher milk yield during early lactation when cows fail to consume sufficient feed (11); 3) increased efficiency of energy utilization (4, 6, 18, 19); and 4) enhanced lipogenic:glucogenic ratio (18, 19). The benefits of fat inclusion in dairy rations may be offset by detrimental effects of fat on rumen fermentation (9, 10, 16, 17,24,25,35). Rumen effects of fats may be diminished by ~sing mixtures of fatty acids composed primarily of saturated acids with high melting points (hard fats) (2, 9, 10, 32, 33). Additionally prilling of hard fats may further reduce rum~ activity of the fat mixture (2, 9, 10). Milk yield and composition have been variably influenced by added fat (2, 3, 12, 23, 27, 30). Variable responses in milk production and composition with added fat may be related to the type (2, 32, 33) and dietary concentration
2864
2865
HARD FATS IN DAIRY COW DffiTS
(3, 6, 10, 33, 35) of fat used in different studies, and to the use of late lactation cows or cows of low producing ability (15, 29). Type and dietary concentration of fat may influence milk yield and composition by depressing rumen fiber digestion (9, 10, 16, 35), but milk production responses have been variable even when protected fats were studied. Most studies have utilized small numbers of cows over short periods, and cows often have been in later stages of lactation. Because effects of fat have been reported to be greater in early than in midlactation (3, 19, 30) and because effects of fats may be more pronounced in older cows with higher producing ability (12), we wanted to examine the effects of a relatively rumeninert fat source fed from calving through 17 to 21 wk after calving in a large number of cows in several commercial herds. Increasing caloric density, energetic efficiency, and lipogenic:glucogenic ratio via the use of fats in dairy cattle rations may enhance reproductive performance. Few studies have reported reproductive data from cows consuming high fat rations (27, 30). Fat inclusion in early lactation rations may mitigate negative energy balance and minimize weight loss. Associated with reduced weight loss may be improvements in reproductive efficiency such as conception rate (CR) and days to first breeding. Extreme BW and condition loss have been negatively correlated with CR in dairy cows (20, 36). Days to first ovulation is longer in cows in greater negative energy balance in the postpartum period (8, 26). Few studies have investigated high fat rations fed from calving through a normal breeding period (up to 150 d postpartum) in large enough numbers of cows to examine reproductive function. Ruesegger and Schultz (27) did not report any significant effects of high fat rations on days to frrst heat, first breeding, or CR in cows consuming whole roasted soybeans; however, cow numbers were few. Schneider et al. (30) observed increased CR in cows fed rations supplemented with rumen-inert fat. Part of our goal was to use large enough numbers of cows to examine reproductive effects of fat supplemented diets in high producing cows. This study reports on the effects of 1) fat in prilled and unprilled form on in vitro fermentation, 2) fat in prilled form on milk production and rumen VFA production in lac-
TABLE 1. Fatty acid composition of the mixture of palmitic, stearic, and oleic acids in unprilled and pri1led forms.
Form of mixture
Fatty acid composition C12~ C~
+
C14~
- - - (g/lOO g) - - 2 ~
~
~w
TI
%
CIS:1
14
14
CW~
1
IFisher Scientific Co., Pittsburgh, PA. 2BP Nutrition Ltd., Wincham, Norwich, Chesire, CW9 6DF, UK.
tating dairy cows in a short-term Latin square, and 3) fat in prilled form on milk production, rumen VFA production, and reproduction in a lactation trial in four herds beginning at the initiation of lactation through 120 to 150 d in milk. MATERIALS AND METHODS In VItro Experiment
The in vitro fermentation procedure followed Goering and Van Soest (14), modified to utilize one-half of their quantities of media and inoculum (9). Fermentations were conducted in 50-ml Erlenmeyer flasks under a COz atmosphere for 20 h in a Dubnoff metabolic shaking incubator. Flasks contained 20 ml of medium, 1 ml of reducing solution, 750 mg of substrate (450 mg of grass hay plus 300 mg of grain), and a mixture of palmitic, stearic, and oleic acids in unprilled (Fisher Scientific Co., Pittsburgh, PA) or priDed (Dairy Fat PriIIs, BP Nutrition Ltd., Wincham, Norwich, Cheshire CW9 6DF UK) forms (Table 1) at 0, 5, 10, 15, or 20% of the substrate. Flasks were inoculated with 5 mI of rumen fluid obtained from a cow fed 3.6 kg of grass hay, 2.3 kg of grain, and .2 kg of tallow daily. Medium contained 1.75 times the level of NaHC03 originally used by Goering and Van Soest (14) in order to maintain pH >6.0 during fermentation. After 20 h, fermentation was stopped by addition of 1 mI of a saturated solution of HgClz. The fermentation medium was centrifuged at 10,000 x g for 10 min. One milliliter Journal of Dairy Science Vol. 73, No. 10, 1990
2866
FERGUSON ET AL.
of 36% metaphosphoric acid was added to 5 ml of supernatant, and the mixture was frozen. Following thawing, the mixture was centrifuged at 15,000 x g for 20 min. Supernatants were assayed for VFA by gas liquid chromatography (1). Production of VFA was calculated as the difference between quantities present at 0 versus 20 h of fermentation. Three experiments were conducted. This allowed for duplicate fermentations with each form and level of the fatty acid mixture. Short-Term Lactation Experiment
Cows in midlactation were fed total mixed rations of com silage, com, and soybean meal (40:43:15% DM basis) plus minerals and vitamin supplements to meet NRC (21) recommendations. Total mixed rations supplemented with 0, 3, 6, or 9% Dairy Fat Prills were offered in a 4 x 4 Latin square experiment with 21-
and Faculty of Agriculture Hebrew University Rehovot 76-100. Israel
ABSTRACT
90 d postcalving. In Pennsylvania, prilled fat had variable effects on milk composition and little effect on milk yield and FCM. Conception rate was improved in cows consuming rations containing prilled fat: first service, 59.1 versus 42.6%; all services, 59.3 versus 40.7%. The inclusion of prilled fat at 2% of DM in dairy cattle rations had slight effects on rumen fermentation, variable effects on milk. yield and composition, and beneficial effects on conception rate. (Key words: dairy cattle, hard fats, production, reproduction)
Adding 0, 5, 10, 15, and 20% of substrate as prilled or unprilled fatty acids [palmitic (47 to 48%), stearic (36 to 37%), and oleic (14%) acids] to an in vitro rumen fennenter had no effect on total VFA production. Acetate:propionate ratio was reduced by fatty acid concentrations of 15 and 20% (prilled and unprilled). In a 4 x 4 Latin square, increasing dietary prilled fatty acids (0, 3, 6, or 9% of OM) decreased OM intake, increased percentage of milk. fat, and had no effect on percentage of milk. protein. Milk. volume and FCM increased with 3% but decreased with 6 and 9% dietary fatty acids. Rumen fluid acetate:propionate decreased with increasing dietary fatty acids. Holstein cows in three herds in Pennsylvania and Friesian cows in an Israeli herd were assigned randomly to receive, from 0 to 110 to 150 d postcalving, diets containing 0 or 2% of OM prilled fat. In Israel, dietary fat increased milk. yield, FCM, and fat percentage during the first
INTRODUCTION
Received September 18, 1989. 1"ceepted May 9, 1990. This research was supported by Grant Number US722-83c from BARD-The United States-Israel Binational A~cu1tuIa1 Research and Development Fund. Present address: Center for Animal Disease and Pr0ductivity, New Bolton Center. University of Peonsylvania, School of Veterinary Medicine, Kennett Square 19382. ~ebrew University of Jerusalem, The Levi Eshkol School of Agriculture, Rehovot, Israel 76-100. ~ent address: Virginia Tech University, Department of Animal Science, Blacksburg, VA 24061-0306. 1990 J Dairy Sci 73:2864-2879
Inclusion of fat, especially rumen inert fat (3, 6, 17, 24), in dairy cattle rations has four immediate benefits: 1) increased caloric density without compromising fiber (11, 19, 24); 2) increased energy intake for higher milk yield during early lactation when cows fail to consume sufficient feed (11); 3) increased efficiency of energy utilization (4, 6, 18, 19); and 4) enhanced lipogenic:glucogenic ratio (18, 19). The benefits of fat inclusion in dairy rations may be offset by detrimental effects of fat on rumen fermentation (9, 10, 16, 17,24,25,35). Rumen effects of fats may be diminished by ~sing mixtures of fatty acids composed primarily of saturated acids with high melting points (hard fats) (2, 9, 10, 32, 33). Additionally prilling of hard fats may further reduce rum~ activity of the fat mixture (2, 9, 10). Milk yield and composition have been variably influenced by added fat (2, 3, 12, 23, 27, 30). Variable responses in milk production and composition with added fat may be related to the type (2, 32, 33) and dietary concentration
2864
2865
HARD FATS IN DAIRY COW DffiTS
(3, 6, 10, 33, 35) of fat used in different studies, and to the use of late lactation cows or cows of low producing ability (15, 29). Type and dietary concentration of fat may influence milk yield and composition by depressing rumen fiber digestion (9, 10, 16, 35), but milk production responses have been variable even when protected fats were studied. Most studies have utilized small numbers of cows over short periods, and cows often have been in later stages of lactation. Because effects of fat have been reported to be greater in early than in midlactation (3, 19, 30) and because effects of fats may be more pronounced in older cows with higher producing ability (12), we wanted to examine the effects of a relatively rumeninert fat source fed from calving through 17 to 21 wk after calving in a large number of cows in several commercial herds. Increasing caloric density, energetic efficiency, and lipogenic:glucogenic ratio via the use of fats in dairy cattle rations may enhance reproductive performance. Few studies have reported reproductive data from cows consuming high fat rations (27, 30). Fat inclusion in early lactation rations may mitigate negative energy balance and minimize weight loss. Associated with reduced weight loss may be improvements in reproductive efficiency such as conception rate (CR) and days to first breeding. Extreme BW and condition loss have been negatively correlated with CR in dairy cows (20, 36). Days to first ovulation is longer in cows in greater negative energy balance in the postpartum period (8, 26). Few studies have investigated high fat rations fed from calving through a normal breeding period (up to 150 d postpartum) in large enough numbers of cows to examine reproductive function. Ruesegger and Schultz (27) did not report any significant effects of high fat rations on days to frrst heat, first breeding, or CR in cows consuming whole roasted soybeans; however, cow numbers were few. Schneider et al. (30) observed increased CR in cows fed rations supplemented with rumen-inert fat. Part of our goal was to use large enough numbers of cows to examine reproductive effects of fat supplemented diets in high producing cows. This study reports on the effects of 1) fat in prilled and unprilled form on in vitro fermentation, 2) fat in prilled form on milk production and rumen VFA production in lac-
TABLE 1. Fatty acid composition of the mixture of palmitic, stearic, and oleic acids in unprilled and pri1led forms.
Form of mixture
Fatty acid composition C12~ C~
+
C14~
- - - (g/lOO g) - - 2 ~
~
~w
TI
%
CIS:1
14
14
CW~
1
IFisher Scientific Co., Pittsburgh, PA. 2BP Nutrition Ltd., Wincham, Norwich, Chesire, CW9 6DF, UK.
tating dairy cows in a short-term Latin square, and 3) fat in prilled form on milk production, rumen VFA production, and reproduction in a lactation trial in four herds beginning at the initiation of lactation through 120 to 150 d in milk. MATERIALS AND METHODS In VItro Experiment
The in vitro fermentation procedure followed Goering and Van Soest (14), modified to utilize one-half of their quantities of media and inoculum (9). Fermentations were conducted in 50-ml Erlenmeyer flasks under a COz atmosphere for 20 h in a Dubnoff metabolic shaking incubator. Flasks contained 20 ml of medium, 1 ml of reducing solution, 750 mg of substrate (450 mg of grass hay plus 300 mg of grain), and a mixture of palmitic, stearic, and oleic acids in unprilled (Fisher Scientific Co., Pittsburgh, PA) or priDed (Dairy Fat PriIIs, BP Nutrition Ltd., Wincham, Norwich, Cheshire CW9 6DF UK) forms (Table 1) at 0, 5, 10, 15, or 20% of the substrate. Flasks were inoculated with 5 mI of rumen fluid obtained from a cow fed 3.6 kg of grass hay, 2.3 kg of grain, and .2 kg of tallow daily. Medium contained 1.75 times the level of NaHC03 originally used by Goering and Van Soest (14) in order to maintain pH >6.0 during fermentation. After 20 h, fermentation was stopped by addition of 1 mI of a saturated solution of HgClz. The fermentation medium was centrifuged at 10,000 x g for 10 min. One milliliter Journal of Dairy Science Vol. 73, No. 10, 1990
2866
FERGUSON ET AL.
of 36% metaphosphoric acid was added to 5 ml of supernatant, and the mixture was frozen. Following thawing, the mixture was centrifuged at 15,000 x g for 20 min. Supernatants were assayed for VFA by gas liquid chromatography (1). Production of VFA was calculated as the difference between quantities present at 0 versus 20 h of fermentation. Three experiments were conducted. This allowed for duplicate fermentations with each form and level of the fatty acid mixture. Short-Term Lactation Experiment
Cows in midlactation were fed total mixed rations of com silage, com, and soybean meal (40:43:15% DM basis) plus minerals and vitamin supplements to meet NRC (21) recommendations. Total mixed rations supplemented with 0, 3, 6, or 9% Dairy Fat Prills were offered in a 4 x 4 Latin square experiment with 21-
